  function ValidateOffer() {
     // Variabili associate ai campi del form_add_offer
     
     var offer_price = document.form_add_offer.offer_price.value;
     var errorLog = document.getElementById("add_offer_error_log")
          
        if((offer_price== "")||(isNaN(offer_price)) ||(parseFloat(offer_price)<=0)) {
           errorLog.innerHTML='offer price must be more than last offer price.';
           document.form_add_offer.offer_price.focus();
           return false;
        }
        else {
           document.form_add_offer.submit();
        }
  }
